VMware vSphere vCenter Server 5.1 now uses a new SSO (Single Sign On) service to authenticate with Microsoft Active Directory when deploying vCenter. If you do not install this services and configure it for AD then you will not be able to use your domain accounts with vCenter 5.1 During the initial install you may get errors when installing SSO. KB 2034374 reports that a error of ” Error 29155 Identity source discovery… Continue reading